Devices of IQ mismatch calibration, and methods thereof

ABSTRACT

The device with IQ mismatch compensation includes a transmitter oscillator, a transmitter module, and a loop-back module. The transmitter module is arranged to up-convert a transmitter signal with the oscillator signal to generate an RF signal. The loop-back module is arranged to down-convert the RF signal with the oscillator signal to determine a transmitter IQ mismatch parameter, and effects of IQ mismatch of the loop-back module are calibrated by inputting a test signal and the oscillator signal before the down-converting of the RF signal. The transmitter module is arranged to reduce effects of IQ mismatch of a transmitter path in the transmitter module according to the transmitter IQ mismatch parameter.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The disclosure relates generally to IQ mismatch calibration, and, moreparticularly to devices of IQ mismatch detection and compensation, andmethods thereof.

2. Description of the Related Art

Wireless communication devices are commonly deployed in wirelesscommunication systems to provide communication services such as voice,multimedia, data, broadcast, and messaging services. In a conventionalwireless communication device such as a mobile phone, a digital basebandcircuit block provides a data stream of complex, digital baseband datato a transmitter, where the transmitted baseband data are often carriedon an orthogonal transmitter signal represented by real components andimaginary components, or, in-phase (I) and quadrature (Q) components. Inthe transmitter, the real component and the imaginary component of thetransmitter signal are processed along a real-component circuit path andthe imaginary component is processed along an imaginary-componentcircuit path, parallel to each other. The digital and analog signalprocessing along the real-component and the imaginary-component circuitpath are all in parallel, and may include multiplexing, filtering, powercontrol, and up-sampling processes, and so on. The parallel signalprocessed transmitter signal is modulated to produce an analog radiofrequency (RF) signal to be amplified and radiated onto the airinterface from an antenna, providing communication data exchange with abase station of the communication system.

Ideally, the real and imaginary components are processed along parallelcircuit paths in the transmitter, and the circuit elements along onepath are perfectly identical, or “matched”, with corresponding circuitelements along the other parallel channel. However, the correspondingcircuit elements along the real and imaginary circuit paths often haveslight or relatively significant differences from each other due tomanufacturing process variations and geometrical layout differences,resulting in non-negligible amplitude differences (“IQ gain mismatch”)and phase differences (“IQ phase mismatch”) between the real andimaginary components that are processed along the parallel paths. Thenon-negligible IQ gain and phase mismatch may result in unacceptabledegraded signal quality.

Thus devices capable of IQ mismatch correction and methods thereof areneeded to increase transmitted signal quality.

BRIEF SUMMARY OF THE INVENTION

An embodiment of a device with IQ mismatch compensation is disclosed,comprising a transmitter oscillator, a transmitter module, and aloop-back module. The transmitter oscillator provides an oscillatorsignal. The transmitter module is arranged to up-convert a transmittersignal with the oscillator signal to generate an RF signal. Theloop-back module is arranged to down-convert the RF signal with theoscillator signal to determine a transmitter IQ mismatch parameter,wherein effects of IQ mismatch of the loop-back module are calibrated byinputting a test signal and the oscillator signal before thedown-converting of the RF signal. The transmitter module is arranged toreduce effects of IQ mismatch of a transmitter path in the transmittermodule according to the transmitter IQ mismatch parameter.

Another device with IQ mismatch compensation is provided, comprising atransmitter module and a loop-back module. The loop-back module is fordown-converting an RF signal to determine a transmitter IQ mismatchparameter. The transmitter module is for up-converting a transmittersignal to generate the RF signal. Wherein the loop-back module isarranged to determine a first mismatch parameter of the transmitter IQmismatch parameter when the transmitter module sets one of an in-phasecomponent and a quadrature component of the transmitter signal to a zerosignal, the loop-back module is arranged to determine a second mismatchparameter of the transmitter IQ mismatch parameter when the transmittermodule sets the other one of the in-phase component and the quadraturecomponent of the transmitter signal to a zero signal; and thetransmitter module is arranged to reduce effects of IQ mismatch of atransmitter path in the transmitter module according to the transmitterIQ mismatch parameter.

Yet another IQ mismatch compensation method is disclosed, comprisingup-converting a transmitter signal with an oscillator signal by atransmitter module to generate an RF signal; down-converting the RFsignal with the oscillator signal to determine a transmitter IQ mismatchparameter by a loop-back module, wherein a test signal and theoscillator signal are inputted to calibrate effects of IQ mismatch ofthe loop-back module before the down-converting of the RF signal; andreducing effects of IQ mismatch of a transmitter path in the transmittermodule according to the determined transmitter IQ mismatch parameter.

Still another IQ mismatch compensation method is shown, wherein atransmitter module is arranged to up-convert a transmitter signal togenerate an RF signal, the IQ mismatch compensation method comprisingdown-converting the RF signal to determine a transmitter IQ mismatchparameter by setting one of an in-phase component and a quadraturecomponent of the transmitter signal to a zero signal to determine afirst mismatch parameter of a transmitter IQ mismatch parameter; andsetting the other one of the in-phase component and the quadraturecomponent of the transmitter signal to a zero signal to determine asecond mismatch parameter of the transmitter IQ mismatch parameter; andreducing effects of IQ mismatch of a transmitter path in the transmittermodule according to the determined transmitter IQ mismatch parameter.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood by referring to thefollowing detailed description with reference to the accompanyingdrawings, wherein:

FIG. 1 is a block diagram of an exemplary wireless communication system.

FIG. 2 is a block diagram of an exemplary transceiver circuit inaccordance with the present invention.

FIG. 3 is a simplified equivalent circuit of the transmitter module 22and the loop-back module 24 in FIG. 2 after the loop-back IQ mismatchcompensation.

FIG. 4 is a block diagram of another exemplary device with IQ mismatchcompensation according to the present invention.

FIG. 5 is a circuit diagram of an exemplary IQ phase mismatchcompensation circuit according to the present invention.

FIG. 6 is a circuit diagram of an exemplary IQ gain mismatchcompensation circuit according to the present invention.

FIG. 7 is a circuit diagram of an exemplary oscillator phase differencecompensation circuit according to the present invention.

FIG. 8 is a flowchart of an exemplary IQ mismatch and oscillator phasedifference detection and compensation method according to presentinvention.

FIG. 9 is a flowchart of an exemplary oscillator phase differencedetection and compensation method according to present invention.

FIG. 10 is a flowchart of an exemplary IQ mismatch detection andcompensation method according to present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a block diagram of an exemplary wireless communication system1, comprising a communication device 10, a base station 12, a controlnode 14, and a service network 16. The communication device 10 iswirelessly coupled to the base station 12, which is further coupled tothe control node 14 and the service network 16.

The wireless communications between the communication device 10 and theservice network 16 may be in compliance with various wirelesstechnologies, such as the Global System for Mobile communications (GSM)technology, General Packet Radio Service (GPRS) technology, EnhancedData rates for Global Evolution (EDGE) technology, Wideband CodeDivision Multiple Access (WCDMA) technology, Code Division MultipleAccess 2000 (CDMA 2000) technology, Time Division-Synchronous CodeDivision Multiple Access (TD-SCDMA) technology, WorldwideInteroperability for Microwave Access (WiMAX) technology, Long TermEvolution (LTE) technology, and others.

The wireless communication system 1 may use a frequency divisionduplexing (FDD) or time division duplexing (TDD) techniques. In the FDDsystem, the communication device 10 and the base station 12 communicatesthrough uplink and downlink communication at different frequencies. Inthe TDD system, the communication device 10 and the base station 12communicates through uplink and downlink communication at differenttime, typically deploys asymmetrical uplink and downlink data rates. Thecommunication device 10 may be a hand-held cellular phone, a laptopcomputer equipped with a wireless adapter, or any other device. Thecommunication device 10 comprises a transceiver module (not shown) forperforming the functionality of wireless transmissions and receptions toand from the base station 12. The transceiver module may comprise abaseband unit (not shown) and an analog unit (not shown). The basebandmodule may comprise hardware to perform baseband signal processingincluding digital signal processing, coding and decoding, and so on. Theanalog module may comprise hardware to perform analog to digitalconversion (ADC), digital to analog conversion (DAC), gain adjusting,modulation, demodulation, and so on. The base station 12 includestransceivers, antenna interface equipment, and power supplies. Theservice network 16 is a radio access network, such as a GSM network, aUMTS network, and so on. The service network 16 provides wirelesscommunication services to the communication device 10. The uplink anddownlink communication between the communication device 10 and the basestation 12 employs orthogonal RF signals comprising in-phase (I) andquadrature (Q) components, thus IQ imbalance correction of the RFsignals is in need to provide increased signal quality under harshtransmission environment.

FIG. 2 is a block diagram of an exemplary transmitter device inaccordance with one embodiment of the present invention, incorporated inthe communication device 10 in FIG. 1. The communication device utilizedthe transmitter device 2 is utilized in either a FDD or TDD system. TheIQ mismatch comprises phase and gain (amplitude) mismatch. Thetransmitter device 2 is capable of IQ mismatch detection andcompensation, and comprises a transmitter oscillator 20, a transmittermodule 22, a loop-back module 24, an oscillator buffer 26, and a testtone generator 28. The transmitter oscillator 20 is coupled to theoscillator buffer 26, subsequently coupled to the transmitter module 22and the loop-back module 24. The transmitter module 22 is coupled to theloop-back module 24. The test tone generator 28 is coupled and feedstest tone signals to the loop-back module 24.

The transmitter module 24 comprises a transmitter baseband module 220and a transmitter analog module 222. The transmitter baseband module 220comprises a transmitter IQ mismatch compensation module 2200. Thetransmitter analog module 222 comprises Digital-to-Analog Converters(DACs) 22200 and 22202, band pass filters 22204 and 22206, mixers 22208and 22210, Programmable Gain Amplifier (PGA) 22212, and a firstfrequency divider 22214. The DAC 22200 is coupled to the band passfilter 22204, then the mixer 22208. The DAC 22202 is coupled to the bandpass filter 22206, then the mixer 22210. The mixers 22208 and 22210 arecoupled together, then to the PGA 22212. The first frequency divider22214 is coupled to the mixers 22208 and 22210 and the transmitteroscillator buffer 26.

The loop-back module 24 comprises a loop-back baseband module 240 and aloop-back analog module 242. The loop-back baseband module 240 comprisesa loop-back IQ mismatch detection and compensation module 2400, atransmitter IQ mismatch detection module 2402, and an oscillator phasedifference detection and compensation module 2404. The loop-back analogmodule 242 comprises mixers 24200 and 24202, band pass filters 22204 and22206, buffers 24208, Analog-to-Digital Converters (ADCs) 24212 and24216, a second frequency divider 24216, and a receiver amplifier 24218.The receiver amplifier 24218 is coupled to the mixers 24200 and 24202.The mixer 24200 is coupled to the band pass filter 24204, the buffer24208, and then to the ADC 24212. The mixer 24202 is coupled to the bandpass filter 24206, the buffer 24210, and then to the ADC 24214. Thesecond frequency divider 24216 is coupled to the mixer 24200 and 24202to provide in-phase and quadrature oscillator signals, respectively.

The signal path along the DAC 22200, the band pass filter 22204, and themixer 22208 is referred to as an I-path of the transmitter module 22.The I-path receives a transmitter signal x(t) to generate an in-phasecomponent of an RF signal. The signal path along the DAC 22202, the bandpass filter 22206, and the mixer 22210 is referred to as a Q-path of thetransmitter analog module 222. The Q-path receives the transmittersignal x(t) to generate a quadrature component of the RF signal. TheI-path and Q-path of the transmitter analog module 222 are both referredto as transmitter paths. Similarly, the signal path along the mixer24200, the band pass filter 24204, and the ADC 24208 is referred to asan I-path of the loop-back analog module 242. The I-path receives the RFsignal r(t) to generate an in-phase component of a down-converted RFsignal. The signal path along the mixer 24202, the band pass filter24206, and the ADC 24210 is referred to as a Q-path of the loop-backanalog module 242. The Q-path receives the RF signal y(t) to generate aquadrature component of the down-converted RF signal. The I-path andQ-path of the transmitter module loop-back analog module 242 are bothreferred to as loop-back paths. The transmitter signal x(t) comprisesuplink data to be transmitted to the node B in a radio access network.

The transmitter oscillator 20 generates and provides an oscillatorsignal to the transmitter module 20 and the loop-back module 24. Theoscillator signal oscillates at an oscillator frequency ω_(TLO) fed tothe transmitter module 22 and the loop-back module 24, providing acarrier signal for modulation and demodulation, respectively. Theoscillator frequency ω_(TLO) is a radio frequency (RF) that may be 900MHz, 1900 MHz, or 2100 MHz in WCDMA systems, or may be 900 MHz, 2100MHz, or 2.6 GHz in LTE systems, or others depending on the radio accesstechnology (RAT) in use.

The transmitter module 22 converts the transmitter signal x(t) fromdigital to analog at the DAC 22200 and the DAC 22202, filters offunwanted signals in the transmitter signal x(t) at the filters 22204 and22206, and up-converts the transmitter signal x(t) with the oscillatorsignal to generate the RF signal y(t). The transmitter signal x(t) andRF signal y(t) are orthogonal signals comprising an in-phase componentand a quadrature component. The in-phase component and the quadraturecomponent of the RF signal y(t) are combined and transmitted to the PGA22212, which amplifies the RF signal y(t) according to an allocatedpower before being transmitted by an antenna (not shown).

Before using the loop-back module 24 to detect a transmitter IQ mismatchparameter and compensate for a transmitter IQ mismatch in thetransmitter path, the loop-back module 24 needs to be calibrated so thatno loop-back IQ mismatch remains therein. The loop-back module 24receives a test tone signal from the test tone generator 28 and theoscillator signal from the transmitter buffer 26 to determine and reduceeffects of IQ mismatch of a loop-back path in the loop-back module. Theloop-back module 24 then down-converts the RF signal y(t) with theoscillator signal to determine the transmitter IQ mismatch parameterindicating the transmitter IQ mismatch in the transmitter path. In someembodiments, the transmitter 2 is utilized in a WCDMA communicationdevice, and the loop-back module 24 detects the power level of theamplified RF signal, thereby controlling a PGA gain of the PGA 22212 toproduce the amplified RF signal at the allocated power level.

The transmitter IQ mismatch compensation module 220 then further reduceseffects of the transmitter IQ mismatch of a transmitter path to thetransmitter signal x(t) according to the transmitter IQ mismatchparameter, before transmitting the IQ mismatch reduced transmittersignal x(t) to the transmitter analog module 222.

FIG. 3 is a simplified equivalent circuit of the transmitter module 22and the loop-back module 24 in FIG. 2 after the loop-back IQ mismatchcompensation, illustrating effects of the transmitter IQ mismatch in thetransmitter module 22. The equivalent circuit 3 comprises a transmittermodule 30 and a loop-back module 31. The transmitter module 30 comprisesmixers 300 and 302, and adders 304, 306, and 308. The mixer 300 iscoupled to the adder 304, and subsequently to the adder 308. The mixer302 is coupled to the adder 306, and then to the adder 308. Theloop-back module 31 comprises mixers 310, 312, and 314, and an adder316. The mixer 312 is coupled to the mixer 314, then to the adder 316.The mixer 310 is coupled to the adder 316.

The transmitter signal x(t) is an orthogonal signal comprising anin-phase component I and a quadrature component Q, i.e., x(t)=I+jQ. Thesignal path along the mixer 300 and the adder 304 is referred to as anI-path of the transmitter module 30. The I-path receives an transmittersignal x(t) to generate an in-phase component of an RF signal. Thesignal path along the mixer 302 and the adder 306 is referred to as aQ-path of the transmitter module 30. The Q-path receives the transmittersignal x(t) to generate a quadrature component of the RF signal. TheI-path and Q-path of the transmitter module 30 are both referred to astransmitter paths.

In absence of the transmitter IQ mismatch, the RF signal y(t) is shownby:y(t)=I cos(ω_(TLO) t)+Q sin(ω_(TLO) t)  Equation (1)where ω_(TLO) is an oscillator frequency of a transmitter oscillator(not shown), and

t is time.

In presence of the transmitter IQ mismatch, a phase mismatch on theI-path is represented by θ_(I) and a phase mismatch on the Q-path isrepresented by θ_(Q), a gain mismatch on the I-path is represented by(1+ε_(I)) and a gain mismatch on the Q-path is represented by (1+ε_(I)).The RF signal y(t) is represented by:

$\begin{matrix}{{{y(t)} = {\frac{1}{2}\left( {{K_{1} \cdot {x(t)}} + {K_{2}^{*} \cdot {x^{*}(t)}}} \right){\mathbb{e}}^{j\;\omega_{TLO}t}}}{where}\mspace{14mu}{{K_{1} = {{\frac{1}{2}\left( {1 + ɛ_{I}} \right){\mathbb{e}}^{j\;\theta_{I}}} + {\frac{1}{2}\left( {1 + ɛ_{Q}} \right){\mathbb{e}}^{{- j}\;\theta_{Q}}}}},{and}}{{K_{2} = {{\frac{1}{2}\left( {1 + ɛ_{I}} \right){\mathbb{e}}^{{- j}\;\theta_{I}}} - {\frac{1}{2}\left( {1 + ɛ_{Q}} \right){\mathbb{e}}^{j\;\theta_{Q}}}}},}} & {{Equation}\mspace{14mu}(2)}\end{matrix}$

Because the loop-back IQ mismatch compensation is completed, the phaseand gain IQ mismatch is absent at the loop-back module 31. The mixer 310down-converts the RF signal y(t) with an in-phase component (cos ω_(TLO)t) of an oscillator signal to generate an in-phase component of thedown-converted RF signal r(t). The mixer 312 down-converts the RF signaly(t) with a quadrature component (sin ω_(TLO) t) of an oscillator togenerate a quadrature component of the down-converted RF signal r(t).The signal path along the mixer 310 is referred to as an I-path of theloop-back module 31. The signal path along the mixer 312 and the adder314 is referred to as a Q-path of the loop-back module 31. The I-pathand Q-path of the loop-back module 31 are referred to as loop-backpaths.

The in-phase and quadrature components of the down-converted RF signalare combined at the adder 316. The down-converted RF signal r(t) equals:

$\begin{matrix}\begin{matrix}{{r(t)} = {\frac{1}{2}\left( {{K_{1} \cdot {x(t)}} + {K_{2}^{*} \cdot x^{*}}} \right)}} \\{= {\begin{bmatrix}i & j\end{bmatrix}\begin{bmatrix}r_{I} \\r_{Q}\end{bmatrix}}} \\{= {{\begin{bmatrix}i & j\end{bmatrix}\begin{bmatrix}{\left( {1 + ɛ_{I}} \right)\cos\;\theta_{I}} & {{- \left( {1 + ɛ_{Q}} \right)}\sin\;\theta_{Q}} \\{\left( {1 + ɛ_{I}} \right)\sin\;\theta_{I}} & {\left( {1 + ɛ_{Q}} \right)\cos\;\theta_{Q}}\end{bmatrix}}\begin{bmatrix}I \\Q\end{bmatrix}}}\end{matrix} & {{Equation}\mspace{14mu}(3)}\end{matrix}$The down-converted RF signal r(t) is transmitted to the loop-backbaseband module 240 in FIG. 2 to determine the transmitter IQ mismatchparameter.

Referring to FIG. 2, the transceiver circuit 2 is capable of reducingeffects from decreased orthogonally between the in-phase and quadraturecomponents of an orthogonal signal in the transmitter module 22, or atransmitter phase or gain IQ mismatch. The transceiver 2 detects thetransmitter IQ mismatch represented by the transmitter IQ mismatchparameter, then reduces or removes the transmitter IQ mismatch accordingto the transmitter IQ mismatch parameter. The transceiver 2 detects thetransmitter IQ mismatch by determining an I-path IQ mismatch on theI-path of the transmitter module 22 with reference to a quadraturecomponent of 0 on the Q-path of the transmitter module 22 and a Q-pathIQ mismatch on the Q-path of the transmitter module 22 with reference toa in-phase component of 0 on the I-path of the transmitter module 22,and then determines the transmitter IQ mismatch between the I-phase andQ-path according to the I-path IQ mismatch and Q-path IQ mismatch.

After the loop-back IQ mismatch at the loop-back module 24 iscompensated for, the transceiver 2 may detect and compensate for thetransmitter IQ mismatch using the loop-back path. The transmitterbaseband module 220 sets one of an in-phase component and a quadraturecomponent of the transmitter signal to a zero signal to derive a firstmismatch parameter of the transmitter IQ mismatch parameter, and setsthe other one of the in-phase component and the quadrature component ofthe transmitter signal to a zero signal to derive a second mismatchparameter of the transmitter IQ mismatch parameter. In one example, thetransmitter baseband module 220 sets the in-phase component x_(I)(t) ofthe transmitter signal to a first non-zero signal I′ and the quadraturecomponent x_(Q)(t) of the transmitter signal to a zero signal todetermine an I-path mismatch parameter (first mismatch parameter), andsets the in-phase component x_(I)(t) of the transmitter signal to a zerosignal and the quadrature component x_(Q)(t) of the transmitter signalto a second non-zero signal Q′ to determine a Q-path mismatch parameter(second mismatch parameter). The transmitter IQ mismatch detectionmodule 2402 then determines the transmitter IQ mismatch parametercomprises based on the I-path mismatch parameter and the Q-path mismatchparameter, so that the transmitter IQ mismatch compensation module 2200can use the transmitter IQ mismatch parameter to reduce the effects ofthe transmitter IQ mismatch. The first non-zero signal I′ may be a DCsignal, a sinusoidal signal, or any signal or signal combination that isnot 0. For example, the first non-zero signal may be sin(ωt). The secondnon-zero signal Q′ may be a DC signal, a sinusoidal signal, or anysignal or signal combination that is not 0. The second non-zero signalmay be, for example, sin(ωt). The first and second non-zero signals maybe identical or different. The identical first and second non-zerosignals may simplify the determination of the transmitter IQ mismatchparameter. Matched in-phase and quadrature components of the orthogonalsignal are characterized by no DC difference, or DC offset, to eachother, an orthogonal relationship, or 90 degree out-of-phase, and equalamplitude, or a gain of 1. In embodiments of the present invention, thetransmitter IQ mismatch may be a phase mismatch and/or an amplitude(gain) mismatch.

In one embodiment, the transmitter IQ mismatch parameter indicates aphase mismatch of the signals on the I-path and the Q-path of thetransmitter module 22. The transmitter baseband module 220 sets thein-phase component x_(I)(t) of the transmitter signal to the firstnon-zero signal I′ and the quadrature component x_(Q)(t) of thetransmitter signal to the zero signal to generate the down-converted RFsignal r(t), represented by:

$\begin{matrix}\begin{matrix}{{r_{I - {Path}}(t)} = {\begin{bmatrix}i & j\end{bmatrix}\begin{bmatrix}r_{I\_ IPATH} \\r_{Q\_ IPATH}\end{bmatrix}}} \\{= {\begin{bmatrix}i & j\end{bmatrix}\begin{bmatrix}{\left( {1 + ɛ_{I}} \right)\cos\;{\theta_{I} \cdot I^{\prime}}} & 0 \\{\left( {1 + ɛ_{I}} \right)\sin\;{\theta_{I} \cdot I^{\prime}}} & 0\end{bmatrix}}}\end{matrix} & {{Equation}\mspace{14mu}(4)}\end{matrix}$The transmitter IQ mismatch detection module 2402 determines the I-pathmismatch parameter θ_(I) according to the in-phase component and thequadrature component of the down-converted RF signal r(t), where:θ_(I)≈tan θ_(I) =r _(Q)(I′,0)/r _(I)(I′,0)  Equation (5)The transmitter baseband module 220 sets the in-phase component x_(I)(t)of the transmitter signal to the zero signal and the quadraturecomponent x_(Q)(t) of the transmitter signal to the first non-zerosignal Q′ to generate the down-converted RF signal r(t), represented by:

$\begin{matrix}\begin{matrix}{{r_{Q - {Path}}(t)} = {\begin{bmatrix}i & j\end{bmatrix}\begin{bmatrix}r_{I\_ QPATH} \\r_{Q\_ QPATH}\end{bmatrix}}} \\{= {\begin{bmatrix}i & j\end{bmatrix}\begin{bmatrix}0 & {{- \left( {1 + ɛ_{Q}} \right)}\sin\;{\theta_{Q} \cdot Q^{\prime}}} \\0 & {\left( {1 + ɛ_{Q}} \right)\sin\;{\theta_{Q} \cdot Q^{\prime}}}\end{bmatrix}}}\end{matrix} & {{Equation}\mspace{14mu}(6)}\end{matrix}$The transmitter IQ mismatch detection module 2402 determines the Q-pathmismatch parameter θ_(Q) according to the in-phase component and thequadrature component of the down-converted RF signal r(t) as follows:θ_(Q)≈tan θ_(Q) =r _(I)(0,Q′)/r _(Q)(0,Q′)  Equation (7)The transmitter IQ mismatch detection module 2402 determines thetransmitter IQ mismatch parameter θ according to the I-path mismatchparameter θ_(I) and the Q-path mismatch parameter θ_(Q). In oneembodiment, the transmitter IQ mismatch detection module 2402 determinesthe transmitter IQ mismatch parameter θ by determining a difference ofthe I-path mismatch parameter and the Q-path mismatch parameter, i.e.,θ=θ_(I)−θ_(Q). The transmitter IQ mismatch parameter θ may betransmitted and kept at a register, or any memory unit in thetransmitter IQ mismatch compensation module 2200, so that thetransmitter baseband module 220 can access the memory unit to obtain thetransmitter IQ mismatch parameter θ and compensate for the transmittersignal x(t) before outputting the compensated transmitter signal x(t) tothe transmitter analog module 222. The transmitter IQ mismatchcompensation module 220 then reduces the effects of the IQ mismatch ofthe transmitter path in the transmitter module 22 according to a phasecompensation matrix of the transmitter IQ mismatch parameter:

$\begin{matrix}{M_{\theta} = \begin{bmatrix}1 & {{- \tan}\;\theta} \\{{- \tan}\;\theta} & 1\end{bmatrix}} & {{Equation}\mspace{14mu}(8)}\end{matrix}$The transmitter IQ mismatch compensation module 220 then reduces effectsof IQ mismatch of a transmitter path in the transmitter module 22according to the phase compensation matrix of the transmitter IQmismatch parameter. The phase compensation matrix M_(θ) may beimplemented by a circuit depicted in FIG. 5.

In another embodiment, the transmitter IQ mismatch parameter indicates again mismatch between an I-path and a Q-path of the transmitter module22. The transmitter baseband module 220 sets the in-phase componentx_(I)(t) of the transmitter signal to the first non-zero signal I′ andthe quadrature component x_(Q)(t) of the transmitter signal to the zerosignal to generate the down-converted RF signal r(t), represented by theEquation (4). The transmitter IQ mismatch detection module 2402determines the I-path mismatch parameter (1+ε_(I)) according to thein-phase component I′ of the transmitter signal, in-phase componentr_(I)(I′, 0) and the quadrature component r_(Q)(I′, 0) of thedown-converted RF signal, as shown by:

$\begin{matrix}{{1 + ɛ_{I}} = \frac{\sqrt{\left( {r_{I\_ IPATH}^{2} + r_{Q\_ IPATH}^{2}} \right)}}{I^{\prime}}} & {{Equation}\mspace{14mu}(9)}\end{matrix}$The transmitter baseband module 220 sets the in-phase component x_(I)(t)of the transmitter signal to the zero signal and the quadraturecomponent x_(Q)(t) of the transmitter signal to the first non-zerosignal Q′ to generate the down-converted RF signal r(t), shown asEquation (6).The transmitter IQ mismatch detection module 2402 determines the Q-pathmismatch parameter (1+ε_(Q)) according to the quadrature component Q′ ofthe transmitter signal, the in-phase component r_(I)(0, Q′) and thequadrature component r_(Q)(0, Q′) of the down-converted RF signal, asshown by:

$\begin{matrix}{{1 + ɛ_{Q}} = \frac{\sqrt{\left( {r_{I\_ QPATH}^{2} + r_{Q\_ QPATH}^{2}} \right)}}{Q^{\prime}}} & {{Equation}\mspace{14mu}(10)}\end{matrix}$The transmitter IQ mismatch detection module 2402 determines the gainmismatch G between the I-path and the Q-path according to the I-pathmismatch parameter (1+ε_(I)) and the Q-path mismatch parameter(1+ε_(Q)). The loop-back module 24 determines the transmitter IQmismatch parameter G by:

$\begin{matrix}{G = {\frac{\left( {1 + ɛ_{I}} \right)}{\left( {1 + ɛ_{Q}} \right)} = {\frac{\sqrt{\left( {r_{I\_ IPATH}^{2} + r_{Q\_ IPATH}^{2}} \right)}}{\left( {r_{I\_ QPATH}^{2} + r_{Q\_ QPATH}^{2}} \right)} \cdot \frac{Q^{\prime}}{I^{\prime}}}}} & {{Equation}\mspace{14mu}(11)}\end{matrix}$where:

-   -   (1+ε_(Q)) is the I-path mismatch parameter;    -   (1+ε_(Q)) is the Q-path mismatch parameter;    -   r_(I) _(—) _(IPATH) ²(t) and r_(Q) _(—) _(IPATH) ²(t) are the        in-phase and quadrature component of the down-converted RF        signal r(t) respectively when the in-phase component x_(I)(t) of        the transmitter signal is the first non-zero signal I′ and the        quadrature component x_(Q)(t) of the transmitter signal is a        zero signal;    -   r_(I) _(—) _(QPATH) ²(t) and r_(Q) _(—) _(QPATH) ²(t) are the        in-phase and quadrature component of the down-converted RF        signal r(t) respectively when the in-phase component x_(I)(t) of        the transmitter signal is a zero signal and the quadrature        component x_(Q)(t) of the transmitter signal is the second        non-zero signal Q′; and    -   I′ is the first non-zero in-phase component x_(I)(t) of the        transmitter signal, and Q′ is the second non-zero quadrature        component x_(Q)(t) of the transmitter signal.        The transmitter IQ mismatch parameter G may be transmitted and        kept at a register, or any memory unit in the transmitter IQ        mismatch compensation module 2200, so that the transmitter        baseband module 220 can access the memory unit to obtain the        transmitter IQ mismatch parameter G and compensate for the        transmitter signal x(t) before outputting the compensated        transmitter signal to the transmitter analog module 222. The        transmitter baseband module 220 then reduces the effects of the        IQ mismatch of the transmitter path in the transmitter module 22        according to a gain compensation matrix of the transmitter IQ        mismatch parameter:

$\begin{matrix}{M_{G} = \begin{bmatrix}1 & 0 \\0 & \frac{\left( {1 + ɛ_{I}} \right)}{\left( {1 + ɛ_{Q}} \right)}\end{bmatrix}} & {{Equation}\mspace{14mu}(12)}\end{matrix}$The phase compensation matrix M_(G) may be implemented by a circuitdepicted in FIG. 6. In one embodiment, the first non-zero signal I′equals the first non-zero signal Q′, so that the transmitter IQ mismatchdetection module 2402 can determine the gain mismatch between the I-pathand the Q-path only according to the in-phase component r_(I)(I′, 0) andthe quadrature component r_(Q)(I′, 0) of the down-converted RF signal,and the in-phase component r_(I)(0, Q′) and the quadrature componentr_(Q)(0, Q′) of the down-converted RF signal, i.e.:

$\begin{matrix}{G = {\frac{\left( {1 + ɛ_{I}} \right)}{\left( {1 + ɛ_{Q}} \right)} = {\frac{\sqrt{\left( {{r_{I\_ IPATH}^{2}(t)} + {r_{Q\_ IPATH}^{2}(t)}} \right)}}{\left( {{r_{I\_ QPATH}^{2}(t)} + {r_{Q\_ QPATH}^{2}(t)}} \right)}.}}} & {{Equation}\mspace{14mu}(13)}\end{matrix}$The transmitter IQ mismatch compensation module 220 then reduces effectsof IQ mismatch of a transmitter path in the transmitter module 22according to the gain compensation matrix of the transmitter IQ mismatchparameter.

The first frequency divider 22216 divides the oscillation frequency ofthe oscillator signal by two to generate the first oscillator signal,and up-converts the transmitter signal with the first oscillator signalto generate the RF signal, and the second frequency divider 24216divides the oscillation frequency of the oscillator signal by two togenerate the second oscillator signal, and down-converts the transmittersignal with the second oscillator signal to generate a baseband signal.The first and second oscillator signals to up-convert the transmittersignal x(t) and down-convert the RF signal y(t) are provided from thefirst frequency divider 22216 and the second frequency divider 24216separately, resulting in different oscillator signal paths to theup-converted mixers 22208, 22210 and down-converted mixers 24200, 24202.Since the first and second oscillator signals are produced throughdifferent circuit elements and paths, there is an oscillator phasedifference between the first and second oscillator signals, rendering anoscillator phase difference φ that needs to be compensated for. Theoscillator phase difference φ is a phase difference of the signals onthe transmitter path and the loopback path, arising from differentoscillator signal paths to the up-converted mixers of the transmittermodule 22 and the down-converted mixers of the loop-back module 24.

The oscillator phase difference φ is derived by the down-converted RFsignal r(t). The transmitter baseband module 220 sets the in-phase andquadrature components of the transmitter signal to zero signals todetermine the down-converted RF signal r(t) as a first oscillator phasedifference parameter r_(LO1)(t) at the oscillator phase differencedetection and compensation module 2404. The first oscillator phasedifference parameter represents a phase difference of the first andsecond oscillator signals when the in-phase and quadrature components ofthe transmitter signal are 0. The transmitter baseband module 220 setsone of an in-phase component and a quadrature component of thetransmitter signal to a zero signal to derive a first mismatch parameterof the transmitter IQ mismatch parameter. Specifically, the transmitterbaseband module 220 may set the in-phase component x_(I)(t) of thetransmitter signal to a non-zero constant signal and the quadraturecomponent x_(Q)(t) of the transmitter signal to a zero signal todetermine the down-converted RF signal r(t) as a second oscillator phasedifference parameter r_(LO2)(t) at the oscillator phase differencedetection and compensation module 2404. The second oscillator phasedifference parameter represents a phase difference of the first andsecond oscillator signals when the in-phase component of the transmittersignal is a DC voltage and the quadrature components of the transmittersignal is 0.

Next the oscillator phase difference detection and compensation module2404 determines an oscillator phase difference parameter according tothe first and second oscillator phase difference parameters r_(LO1)(t)and r_(LO2)(t), and reduces the oscillator phase difference φ betweenthe first and second oscillator signals according to the oscillatorphase difference parameter (−θ_(I)−φ). The oscillator phase differencedetection and compensation module 2404 determines the oscillator phasedifference parameter (−θ_(I)−φ) according to a difference of the firstand second oscillator phase difference parameters, or,(−θ_(I)−φ)=r _(LO1)(t)−r _(LO2)(t)  Equation (14)

The oscillator phase difference detection and compensation module 2404performs a digital rotation operation on the down-converted RF signalr(t) with the oscillator phase difference parameter (−θ_(I)−φ) to reduceor remove the oscillator phase difference φ, resulting in a residuephase mismatch −θ_(I) in the oscillator phase difference compensatedsignal r(t). The residue phase mismatch −θ_(I) may be subsequentlyremoved by the transmitter IQ mismatch compensation module 2200 usingthe transmitter IQ mismatch detection and compensation method of theembodiment of the present invention. Thus the oscillator phasedifference detection and compensation module 2404 is configured toreduce the oscillator phase difference prior to the transmitter modulereducing the transmitter IQ mismatch of the transmitter path. Thedigital rotation of an angle (−θ₁−φ) may be implemented by a circuitprovided in FIG. 7.

A receiver device (not shown) may be incorporated with the transmitterdevice 2 to form a transceiver device (not shown) in the communicationdevice 10 in FIG. 1. The receiver device receives a downlink RF signalfrom the base station 12, down-converts the downlink RF signal byreceiver mixers (not shown), and converts to digital baseband signals byreceiver ADCs to be processed in a receiver baseband module (not shown).The downlink RF signal is also an orthogonal signal.

Those skilled in the art will recognize that some components notillustrated may be incorporated in the I-path and Q-path of thetransmitter device 2, such as various low-pass, high-pass, and band-passfilters designed to remove unwanted signal components and buffer stagesto enhance signal strength. However, the various filtering and buffercomponents introduced to the I-path and Q-path of the transceiver 1 mayincrease the phase and amplitude differences or mismatch between thein-phase and quadrature components of the signals in the transmitterdevice 2.

While various circuit functions are performed by different modules inthe transmitter device 2, the modules may be separated, combined, orpartially combined to perform the circuit functions illustrated in theembodiments of the present invention, such that the circuit functionsmay also be separated, combined, or partially combined without deviatingfrom the principle of the invention.

FIG. 4 is a block diagram of another exemplary transmitter device 4capable of IQ mismatch compensation according to one embodiment of thepresent invention.

The transmitter device 4 is identical to the transmitter device 2 inFIG. 2, except that the transmitter module 42 and the loop-back module44 employ different sources of oscillator signals S_(osc1), S_(osc2).The oscillator signals S_(osc1), S_(osc2) provide substantially the sameoscillator frequency and are originated from two separated oscillatorunits (not shown). The transmitter device 4 uses the same transmitter IQmismatch compensation technique as explained in the embodiments in thetransmitter device 2.

FIG. 5 is a circuit diagram of an exemplary IQ phase mismatchcompensation circuit 5 according to one embodiment of the presentinvention, incorporated in the transmitter IQ mismatch compensationmodule 2200 in FIG. 2 or the transmitter IQ mismatch compensation module4200 in FIG. 4. The IQ phase mismatch compensation circuit 5 comprisesmixers 50 and 52, and adders 54 and 56. The mixer 50 is coupled to theadder 54. The mixer 52 is coupled to the adder 56. The mixer 50 adjustsa phase of the quadrature component of the transmitter signal by (−θ/2),where (θ/2) is the gain IQ mismatch. Similarly, the mixer 52 adjusts aphase of the in-phase component of the transmitter signal by (−θ/2),where (θ/2) is the gain IQ mismatch. The adder 54 combines the in-phasecomponent of the transmitter RF signal and the adjusted quadraturecomponent of the transmitter signal to reduce the gain IQ mismatch andprovide a compensated in-phase component of the transmitter RF to thetransmitter analog module in FIG. 2 or FIG. 4. Likewise, the adder 56combines the quadrature component of the transmitter RF signal and theadjusted in-phase component of the transmitter signal to reduce thephase IQ mismatch and provide a compensated quadrature component of thetransmitter RF to the transmitter analog module in FIG. 2 or FIG. 4.

FIG. 6 is a circuit diagram of an exemplary IQ gain mismatchcompensation circuit 6 according to one embodiment of the presentinvention, incorporated in the transmitter IQ mismatch compensationmodule 2200 in FIG. 2 or the transmitter IQ mismatch compensation module4200 in FIG. 4. The IQ gain mismatch compensation circuit 6 comprises amixer 60. The mixer 60 adjusts an amplitude of the quadrature componentof the transmitter signal by a factor (1+ε_(I))/(1+ε_(Q)), so that anamplitude of the in-phase component of the transmitter signal issubstantially equivalent to the amplitude of the quadrature component ofthe transmitter signal, thereby providing the gain IQ mismatchcompensation.

FIG. 7 is a circuit diagram of an exemplary oscillator phase differencecompensation circuit 7 according to one embodiment of the presentinvention, incorporated in the oscillator phase difference detection andcompensation module 2404 in FIG. 2 or the transmitter oscillator phasedifference detection and compensation module 4404 in FIG. 4. Theoscillator phase difference compensation circuit 7 comprises mixers 70and 72. The mixer 70 adjusts a phase of the in-phase component of thedown-converted RF signal by (−θ_(I)−φ) to reduce the oscillator phasedifference. The mixer 72 adjusts a phase of the quadrature component ofthe down-converted RF signal by (−θ_(I)φ). The adjusted in-phase andquadrature components of the down-converted RF signal may be transmittedto the transmitter IQ mismatch detection module in FIG. 2 or FIG. 4 forsignal processing.

FIG. 8 is a flowchart of an exemplary IQ and oscillator phase differencedetection and compensation method according to one embodiment of thepresent invention. The compensation method 8 may incorporate the IQmismatch compensation circuit in FIG. 2. The IQ mismatch comprises phaseand gain mismatch. The method is used in either a frequency divisionduplexing or a time division duplexing system.

Upon startup of the IQ and oscillator phase difference detection andcompensation method 8, the transmitter circuit 2 is initiated in stepS800 prior to uplink data transmission.

In step S806, the loop-back module 24 receives the test signal and theoscillator signal to determine and reduce the effects of the IQ mismatchof the loop-back path. The IQ mismatch of the loop-back path needs to becompensated for prior to the transmitter IQ mismatch compensation, sothat the loop-back module 24 may detect the transmitter IQ mismatch, andthe local IQ mismatch of the loop-back path does not affect thedetection of the transmitter IQ mismatch, thereby allowing for a higheraccuracy in determining the transmitter IQ mismatch. The test signal isprovided from the test tone generator 28.

In step S808, the transmission module 22 sets the transmitter signalx(t) to determine the oscillator phase difference parameter (−θ_(I)−φ).The transmitter oscillator 20 provides the oscillator signal to thetransmission module 22 and the loop-back module 24 to perform modulationand demodulation, respectively. Since the oscillator signals areprovided separately to the transmission module 22 and the loop-backmodule 24, the oscillator phase difference φ is arose from the differentoscillator signal paths to the transmitter module 22 and the loop-backmodule 24. The oscillator phase difference φ between the transmitterpath and the loop-back path has to be compensated for, so that thetransmitter IQ mismatch can be determined at a higher accuracy. FIG. 9discloses a detailed method of determination of the oscillator phasedifference parameter.

In step S810, the loop-back module 24 uses the phase mismatch parameter(−θ_(I)−φ) to reduce the oscillator phase difference φ by digitallyrotating the phase of the down-converted RF signal r(t) by an angle(−θ_(I)−φ). The digital rotation may be implemented by the oscillatorphase difference compensation circuit 7 in the FIG. 7. Thedown-converted RF signal r(t) still comprises the residue phase mismatch(−θ_(I)) after the digital rotation. The residue phase mismatch (−θ_(I))can be reduced or removed using steps S812 and S814. Thus the reductionof the oscillator phase difference in step 810 has to be performed priorto reducing the transmitter IQ mismatch of the transmitter path. FIG. 9discloses the detailed method of the oscillator phase differencecompensation.

In step S812, the loop-back module 24 down-converts the RF signal withthe oscillator signal to determine the transmitter IQ mismatchparameter. The transmitter IQ mismatch parameter may represent the phaseIQ mismatch of the transmitter module 22, the gain IQ mismatch of thetransmitter module 22, or a combination thereof. FIG. 10 discloses adetailed method of determination of the transmitter IQ mismatch.

In step S814, the transmitter module 22 reduces the effects of thetransmitter IQ mismatch of the transmitter path according to thetransmitter IQ mismatch parameter, thereby providing the IQ matched RFsignal for uplink data transmission and decreasing inter-channelinterference and transmit power usage. FIG. 10 provides the detailedmethod of compensation of the transmitter IQ mismatch.

In step S816, the mismatch detection and compensation method 8 iscompleted.

The mismatch detection and compensation method 8 utilizes the loop-backmodule 24 that shares a common oscillator signal source (the transmitteroscillator 20) with the transmitter module 22 to detect and compensatefor the transmitter IQ mismatch, leading to decreased circuit complexityand reduced manufacturing costs.

FIG. 9 is a flowchart of an exemplary oscillator phase differencecalibration method according to one embodiment of the present invention,incorporated in the steps S808 and S810 in the method 8. The oscillatorphase difference calibration method 9 may incorporate the transmittercircuit 2 in FIG. 2 and the oscillator phase difference compensationcircuit 7 in the FIG. 7.

Upon startup, the transmitter circuit 2 is initiated to perform theoscillator phase difference calibration method 9 in step S900. Theoscillator phase difference is the phase difference of the signals onthe transmitter path and the loopback path, arising from differentoscillator signal paths to the transmitter module 22 and the loop-backmodule 24.

In step S902, the transmitter module 22 sets the in-phase and quadraturecomponents of the transmitter signal to zero signals to determine thefirst oscillator phase difference parameter r_(LO1).

In step S904, the transmitter module 22 sets one of the in-phasecomponent and the quadrature component of the transmitter signal to anon-zero constant signal and set the other one of the in-phase componentand the quadrature component of the transmitter signal to a zero signalto determine a second oscillator phase difference parameter. In oneexample, the transmitter module 22 sets the in-phase component of thetransmitter signal to the non-zero constant signal and the quadraturecomponent of the transmitter signal to the zero signal to determinesecond oscillator phase difference parameter r_(LO2). The non-zeroconstant signal may be, for example, 1.8V.

In step S906, the loop-back module 24 determines the oscillator phasedifference parameter (−θ_(I)−φ) according to the difference of the firstand second oscillator phase difference parameters.

In step S908, the loop-back module 24 reduces the oscillator phasedifference φ between the first and second oscillator signals accordingto the oscillator phase difference parameter (−θ_(I)−φ) by theoscillator phase difference compensation circuit 7 in the FIG. 7. Theoscillator phase difference compensation circuit 7 adjusts the phase ofthe down-converted signal r(t) by (−θ_(I)−φ) to compensate for theoscillator phase difference (I), resulting in the residue phase mismatch(−θ_(I)) that needs to be further compensated for. The phasecompensation of the residue phase mismatch (−θ_(I)) can be implementedby the IQ mismatch calibration method 10 in FIG. 10, thus the methods 9and 10 are used in conjunction, and in order, to substantially removethe oscillator phase difference.

In step S910, the oscillator phase difference calibration method 9 isstopped.

FIG. 10 is a flowchart of an exemplary IQ mismatch calibration method 10according to one embodiment of the present invention. The IQ mismatchcalibration method 10 may be incorporated in the steps S812 and S814 inthe method 8, or may be used independently to correct the IQ mismatch ofa transmitter path in a transmitter device. The IQ mismatch calibrationmethod 10 may incorporate the transmitter circuit 2 in FIG. 2, thetransmitter circuit 4 in FIG. 4, the IQ phase mismatch compensationcircuit 5 in FIG. 5, and the IQ gain mismatch compensation circuit 6 inFIG. 6.

Upon startup of the method 10, the transmitter circuit 2 is initiated toperform the IQ mismatch calibration method 10 in step S1000. Next instep S1002, the transmitter module 22 sets one of an in-phase componentand a quadrature component of the transmitter signal to a zero signal toderive a first mismatch parameter of the transmitter IQ mismatchparameter. In one example, the transmitter module 22 sets the in-phasecomponent of the transmitter signal to the first non-zero signal and thequadrature component of the transmitter signal to the zero signal todetermine the I-path mismatch parameter (first mismatch parameter). Thefirst non-zero signal I′ may be a DC signal, a sinusoidal signal, or anysignal or signal combination that is not 0. For example, the firstnon-zero signal may be sin(ωt). The I-path mismatch parameter representsthe phase or gain mismatch of the I-component on the I-path withreference to the zero signal on the Q-path in the transmitter analogmodule 222. In one embodiment, the I-path mismatch parameter representsthe phase mismatch of the signal on the I-path relative to a 0 signal onthe Q-path, and the loop-back module 24 determines the I-path mismatchparameter θ_(I) according to the in-phase component and the quadraturecomponent of the down-converted RF signal (r_(I) _(—) _(IPATH), r_(Q)_(—) _(IPATH)), as expressed in Equation (5). In another embodiment, theI-path mismatch parameter represents the gain mismatch of the signal onthe I-path relative to a 0 signal on the Q-path, and the loop-backmodule 24 determines the I-path mismatch parameter (1+ε_(I)) accordingto the first non-zero signal I′, in-phase component and the quadraturecomponent of the down-converted RF signal (r_(I) _(—) _(IPATH), r_(Q)_(—) _(IPATH)), as expressed by Equation (9).

In step S1004, the transmitter module 22 sets the other one of thein-phase component and the quadrature component of the transmittersignal to a zero signal to derive a second mismatch parameter of thetransmitter IQ mismatch parameter. In one example, the transmittermodule 22 sets the in-phase component of the transmitter signal to thezero signal and the quadrature component of the transmitter signal tothe second non-zero signal to determine the Q-path mismatch parameter(second mismatch parameter). The second non-zero signal Q′ may be a DCsignal, a sinusoidal signal, or any signal or signal combination that isnot 0. The second non-zero signal may be, for example, 1.8V. The firstand second non-zero signal may or may not be identical. The I-pathmismatch parameter represents the phase or gain mismatch of theQ-component on the Q-path with reference to the zero signal on theI-path in the transmitter analog module 222. In one embodiment, theQ-path mismatch parameter represents the phase mismatch of the signal onthe Q-path relative to a 0 signal on the I-path, and the loop-backmodule 24 determines the Q-path mismatch parameter θ_(Q) according tothe in-phase component and the quadrature component of thedown-converted RF signal, as expressed in Equation (7). In anotherembodiment, the Q-path mismatch parameter represents the gain mismatchof the signal on the Q-path relative to a 0 signal on the I-path, andthe loop-back module 24 determines the I-path mismatch parameter(1+ε_(Q)) according to the second non-zero signal Q′, in-phase componentand the quadrature component of the down-converted RF signal (r_(I) _(—)_(PATH), r_(Q) _(—) _(IPATH)), as indicated by Equation (10).

In step S1006, the loop-back module 24 determines the transmitter IQmismatch parameter based on the I-path mismatch parameter and the Q-pathmismatch parameter. The transmitter IQ mismatch parameter represents thephase or gain mismatch between the signal components on the I-path andthe Q-path in the transmitter analog module 222. In one embodiment, thetransmitter IQ mismatch parameter represents the phase mismatch ofsignals on the Q-path and the I-path, and the loop-back module 24determines the transmitter IQ mismatch parameter according to the I-pathphase mismatch parameter θ_(I) and the Q-path phase mismatch parameterθ_(Q). The loop-back module 24 can determine the transmitter IQ mismatchparameter θ by a difference of the I-path phase mismatch parameter θ_(I)and the Q-path phase mismatch parameter θ_(Q), i.e., θ=θ_(I)−θ_(Q). Inanother embodiment, the transmitter IQ mismatch parameter represents thegain mismatch G of signals on the I-path and the Q-path, and theloop-back module 24 determines the transmitter IQ mismatch parameter Gaccording to the I-path gain mismatch parameter (1+ε_(Q)) and the Q-pathgain mismatch parameter (1+ε_(Q)), as expressed in Equation (11). Whenthe first non-zero signal I′ equals the second non-zero signal Q′, theloop-back module 24 determines the transmitter IQ mismatch parameter Gonly according to the in-phase component and the quadrature component ofthe down-converted RF signal, as shown in Equation (13).

In step S1008, the transmitter module 22 reduces the transmitter IQmismatch according to the transmitter IQ mismatch parameter. In oneembodiment, the transmitter module 22 reduces the effects of thetransmitter IQ mismatch according to the phase compensation matrix M_(θ)of the transmitter IQ mismatch parameter, represented by Equation (8).In another embodiment, the transmitter module 22 reduces the effects ofthe transmitter IQ mismatch according to the gain compensation matrixM_(G) of the transmitter IQ mismatch parameter, represented by Equation(12). The gain compensation matrix M_(G) can be realized by the IQ phasemismatch compensation circuit 5 in FIG. 5, and the gain compensationmatrix M_(G) can be implemented by the IQ gain mismatch compensationcircuit 6 in FIG. 6.

In step S1010, the IQ mismatch detection and compensation method 10 iscompleted.

Although the transmitter device 2 is used as an example to explain theoperation of the method 10, the transmitter device 4 may alsoincorporate the method 10 to detect and correct the transmitter IQmismatch thereof. Persons skilled in the arts may adopt the transmitterIQ mismatch calibration method 10 in a transmitter device withoutdeviating from principle of the invention.

As used herein, the term “determining” encompasses calculating,computing, processing, deriving, investigating, looking up (e.g.,looking up in a table, a database or another data structure),ascertaining and the like. Also, “determining” may include resolving,selecting, choosing, establishing and the like.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, information,signals and the like that may be referenced throughout the abovedescription may be represented by voltages, currents, electromagneticwaves, magnetic fields or particles, optical fields or particles or anycombination thereof.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logicdevice, discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller or state machine.

While the invention has been described by way of example and in terms ofpreferred embodiment, it is to be understood that the invention is notlimited thereto. Those who are skilled in this technology can still makevarious alterations and modifications without departing from the scopeand spirit of this invention. Therefore, the scope of the inventionshall be defined and protected by the following claims and theirequivalents.

What is claimed is:
 1. A device with IQ mismatch compensation,comprising: a transmitter oscillator, for providing an oscillatorsignal; a transmitter module, for up-converting a transmitter signalwith the oscillator signal to generate an RF signal; a loop-back module,for down-converting the RF signal with the oscillator signal todetermine a transmitter IQ mismatch parameter, wherein effects of IQmismatch of the loop-back module are calibrated by inputting a testsignal and the oscillator signal before the down-converting of the RFsignal; and wherein the transmitter module is arranged to reduce effectsof IQ mismatch of a transmitter path in the transmitter module accordingto the determined transmitter IQ mismatch parameter.
 2. The device ofclaim 1, wherein the transmitter IQ mismatch parameter indicates a phasemismatch and a gain mismatch of the transmitter path in the transmittermodule.
 3. The device of claim 1, wherein the transmitter signalcomprises an in-phase component and a quadrature component; thetransmitter module is arranged to set the in-phase component of thetransmitter signal to a first non-zero signal and the quadraturecomponent of the transmitter signal to a zero signal to generate a firstdown-converted RF signal, and the loop-back module is arranged todetermine the I-path mismatch parameter according to the firstdown-converted RF signal; the transmitter module is arranged to set thein-phase component of the transmitter signal to the zero signal and thequadrature component of the transmitter signal to a second non-zerosignal to generate a second down-converted RF signal, and the loop-backmodule is arranged to determine the Q-path mismatch parameter accordingto the second down-converted RF signal; and the loop-back module isarranged to determine the transmitter IQ mismatch parameter according tothe I-path mismatch parameter and the Q-path mismatch parameter.
 4. Thedevice of claim 3, wherein the loop-back module is arranged to determinea phase mismatch of the transmitter IQ mismatch parameter by adifference of the I-path mismatch parameter and the Q-path mismatchparameter.
 5. The device of claim 3, wherein the loop-back module isarranged to determine a gain mismatch of the transmitter IQ mismatchparameter by a ratio of the I-path mismatch parameter and the Q-pathmismatch parameter.
 6. The device of claim 3, wherein the first non-zerosignal equals the second non-zero signal.
 7. The device of claim 1,wherein the transmitter signal comprises an in-phase component and aquadrature component, and an oscillator frequency of the oscillatorsignal are divided to generate a first oscillator signal and a secondoscillator signal which are supplied to the transmitter module and theloop-back module, respectively, the transmitter module is arranged toset the in-phase and quadrature components of the transmitter signal tozero signals to determine a first oscillator phase difference parameter,to set one of the in-phase component and the quadrature component of thetransmitter signal to a non-zero constant signal and set the other oneof the in-phase component and the quadrature component of thetransmitter signal to a zero signal to determine a second oscillatorphase difference parameter, and the loop-back module is arranged todetermine an oscillator phase difference parameter according to adifference of the first and second oscillator phase differenceparameters, and to reduce an oscillator phase difference between thefirst and second oscillator signals according to the oscillator phasedifference parameter.
 8. The device of claim 7, wherein the loop-backmodule is arranged to reduce the oscillator phase difference prior tothe transmitter module reducing the transmitter IQ mismatch of thetransmitter path.
 9. A device with IQ mismatch compensation, comprising:a loop-back module, for down-converting an RF signal to determine atransmitter IQ mismatch parameter; a transmitter module, forup-converting a transmitter signal to generate the RF signal, whereinthe loop-back module is arranged to determine a first mismatch parameterof the transmitter IQ mismatch parameter when the transmitter modulesets one of an in-phase component and a quadrature component of thetransmitter signal to a zero signal, the loop-back module is arranged todetermine a second mismatch parameter of the transmitter IQ mismatchparameter when the transmitter module sets the other one of the in-phasecomponent and the quadrature component of the transmitter signal to azero signal; and the transmitter module is arranged to reduce effects ofIQ mismatch of a transmitter path in the transmitter module according tothe first and second mismatch parameters of the transmitter IQ mismatchparameter.
 10. The device of claim 9, wherein the transmitter signalcomprises an in-phase component and a quadrature component; thetransmitter module is arranged to set the in-phase component of thetransmitter signal to a first non-zero signal and the quadraturecomponent of the transmitter signal to the zero signal to generate afirst down-converted RF signal, and the loop-back module is arranged todetermine the I-path mismatch parameter according to the firstdown-converted RF signal; the transmitter module is arranged to set thein-phase component of the transmitter signal to the zero signal and thequadrature component of the transmitter signal to a second non-zerosignal to generate a second down-converted RF signal, and the loop-backmodule is arranged to determine the Q-path mismatch parameter accordingto the second down-converted RF signal; and the loop-back module isarranged to determine the transmitter IQ mismatch parameter according tothe I-path mismatch parameter and the Q-path mismatch parameter.
 11. Thedevice of claim 10, wherein the transmitter IQ mismatch parameter is aphase mismatch between an I-path and a Q-path of the transmitter module,the loop-back module is arranged to determine the phase mismatch by adifference of the I-path mismatch parameter and the Q-path mismatchparameter, and the transmitter module is arranged to reduce the effectsof the IQ mismatch of the transmitter path in the transmitter moduleaccording to a phase compensation matrix of the phase mismatch:$\begin{bmatrix}1 & {{- \tan}\;\theta} \\{{- \tan}\;\theta} & 1\end{bmatrix}.$
 12. The device of claim 10, wherein the transmittersignal comprises an in-phase component and a quadrature component; thetransmitter module is arranged to set the in-phase component of thetransmitter signal to a first non-zero signal and the quadraturecomponent of the transmitter signal to the zero signal to generate thefirst down-converted RF signal, and the loop-back module is arranged todetermine the I-path mismatch parameter according to the firstdown-converted RF signal and the in-phase component of the transmittersignal; the transmitter module is arranged to set the in-phase componentof the transmitter signal to the zero signal and the quadraturecomponent of the transmitter signal to the second non-zero signal togenerate the second down-converted RF signal, and the loop-back moduleis arranged to determine the Q-path mismatch parameter according to thesecond down-converted RF signal and the quadrature component of thetransmitter signal; and the loop-back module is arranged to determinethe transmitter IQ mismatch parameter according to the I-path mismatchparameter and the Q-path mismatch parameter.
 13. The device of claim 12,wherein the transmitter IQ mismatch parameter is a gain mismatch betweenan I-path and a Q-path of the transmitter module, the loop-back moduledetermines the gain mismatch G by a gain equation:$G = {\frac{\left( {1 + ɛ_{I}} \right)}{\left( {1 + ɛ_{Q}} \right)} = {\frac{\sqrt{\left( {r_{I\_ IPATH}^{2} + r_{Q\_ IPATH}^{2}} \right)}}{\left( {r_{I\_ QPATH}^{2} + r_{Q\_ QPATH}^{2}} \right)} \cdot \frac{Q^{\prime}}{I^{\prime}}}}$where: (1+ε_(I)) is the I-path mismatch parameter; (1+ε_(Q)) is theQ-path mismatch parameter; r_(I) _(—) _(IPATH) ² and r_(Q) _(—) _(IPATH)² are the in-phase and quadrature component of the down-converted RFsignal respectively when the in-phase component of the transmittersignal is the first non-zero signal I′ and the quadrature component ofthe transmitter signal is a zero signal; r_(I) _(—) _(IPATH) ² and r_(Q)_(—) _(IPATH) ² are the in-phase and quadrature component of thedown-converted RF signal respectively when the in-phase component of thetransmitter signal is a zero signal and the quadrature component of thetransmitter signal is the second non-zero signal Q′; and I′ is a firstnon-zero in-phase component of the transmitter signal, and Q′ is thesecond non-zero quadrature component of the transmitter signal; and thetransmitter module comprises a transmitter baseband module, coupled tothe loop-back module, reducing the effects of the IQ mismatch of thetransmitter path in the transmitter module according to a gaincompensation matrix of the transmitter IQ mismatch parameter:$\begin{bmatrix}1 & 0 \\0 & \frac{\left( {1 + ɛ_{I}} \right)}{\left( {1 + ɛ_{Q}} \right)}\end{bmatrix}.$
 14. The device of claim 12, wherein the first non-zerosignal equals the second non-zero signal.
 15. The device of claim 9,wherein the transmitter signal comprises an in-phase component and aquadrature component, and an oscillator frequency of the oscillatorsignal are divided to generate a first oscillator signal and a secondoscillator signal which are supplied to the transmitter module and theloop-back module, respectively, the transmitter module is arranged toset the in-phase and quadrature components of the transmitter signal tozero signals to determine a first oscillator phase difference parameter,to set one of the in-phase component and the quadrature component of thetransmitter signal to a non-zero constant signal and set the other oneof the in-phase component and the quadrature component of thetransmitter signal to a zero signal to determine a second oscillatorphase difference parameter, and the loop-back module is arranged todetermine an oscillator phase difference parameter according to adifference of the first and second oscillator phase differenceparameters, and to reduce an oscillator phase difference between thefirst and second oscillator signals according to the oscillator phasedifference parameter.
 16. The device of claim 15, wherein the loop-backmodule is arranged to reduce the oscillator phase difference prior tothe transmitter module reducing the transmitter IQ mismatch of thetransmitter path.
 17. An IQ mismatch compensation method, comprising:up-converting a transmitter signal with an oscillator signal by atransmitter module to generate an RF signal; down-converting the RFsignal with the oscillator signal to determine a transmitter IQ mismatchparameter by a loop-back module, wherein a test signal and theoscillator signal are inputted to calibrate effects of IQ mismatch ofthe loop-back module before the down-converting of the RF signal; andreducing effects of IQ mismatch of a transmitter path in the transmittermodule according to the determined transmitter IQ mismatch parameter.18. The IQ mismatch compensation method of claim 17, wherein thetransmitter IQ mismatch parameter indicates a phase mismatch and a gainmismatch of the transmitter path in the transmitter module.
 19. The IQmismatch compensation method of claim 17, wherein the transmitter signalcomprises an in-phase component and a quadrature component; and the IQmismatch compensation method further comprises: setting the in-phasecomponent of the transmitter signal to a first non-zero signal and thequadrature component of the transmitter signal to a zero signal togenerate a first down-converted RF signal; determining the I-pathmismatch parameter according to the first down-converted RF signal;setting the in-phase component of the transmitter signal to the zerosignal and the quadrature component of the transmitter signal to asecond non-zero signal to generate a second down-converted RF signal;determining the Q-path mismatch parameter according to the seconddown-converted RF signal; and determining the transmitter IQ mismatchparameter according to the I-path mismatch parameter and the Q-pathmismatch parameter.
 20. The IQ mismatch compensation method of claim 19,wherein the step of determining the transmitter IQ mismatch parametercomprises determining a phase mismatch of the transmitter IQ mismatchparameter by a difference of the I-path mismatch parameter and theQ-path mismatch parameter.
 21. The IQ mismatch compensation method ofclaim 19, wherein the step of determining the transmitter IQ mismatchparameter comprises determining a gain mismatch of the transmitter IQmismatch parameter by a ratio of the I-path mismatch parameter and theQ-path mismatch parameter.
 22. The IQ mismatch compensation method ofclaim 19, wherein the first non-zero signal equals the second non-zerosignal.
 23. The IQ mismatch compensation method of claim 17, wherein thetransmitter signal comprises an in-phase component and a quadraturecomponent, and the IQ mismatch compensation method further comprises:setting the in-phase and quadrature components of the transmitter signalto zero signals to determine a first oscillator phase differenceparameter setting one of the in-phase component and the quadraturecomponent of the transmitter signal to a non-zero constant signal andthe other one of the in-phase component and the quadrature component ofthe transmitter signal to a zero signal to determine a second oscillatorphase difference parameter; determining an oscillator phase differenceparameter according to a difference of the first and second oscillatorphase difference parameters; and the loop-back module reducing anoscillator phase difference between the first and second oscillatorsignals according to the oscillator phase difference parameter.
 24. TheIQ mismatch compensation method of claim 23, wherein the step ofreducing the oscillator phase difference is performed prior to the stepof reducing the transmitter IQ mismatch of the transmitter path.
 25. AnIQ mismatch compensation method, wherein a transmitter module isarranged to up-convert a transmitter signal to generate an RF signal,the IQ mismatch compensation method comprising: down-converting the RFsignal to determine a transmitter IQ mismatch parameter by setting oneof an in-phase component and a quadrature component of the transmittersignal to a zero signal to determine a first mismatch parameter of atransmitter IQ mismatch parameter; and setting the other one of thein-phase component and the quadrature component of the transmittersignal to a zero signal to determine a second mismatch parameter of thetransmitter IQ mismatch parameter; and reducing effects of IQ mismatchof a transmitter path in the transmitter module according to the firstand second mismatch parameters of the determined transmitter IQ mismatchparameter.
 26. The IQ mismatch compensation method of claim 25, whereinthe transmitter signal comprises an in-phase component and a quadraturecomponent; setting the in-phase component of the transmitter signal to afirst non-zero signal and the quadrature component of the transmittersignal to the zero signal to generate a first down-converted RF signal;determining the I-path mismatch parameter according to the firstdown-converted RF signal; setting the in-phase component of thetransmitter signal to the zero signal and the quadrature component ofthe transmitter signal to a second non-zero signal to generate a seconddown-converted RF signal; determining the Q-path mismatch parameteraccording to the second down-converted RF signal; and determining thetransmitter IQ mismatch parameter according to the I-path mismatchparameter and the Q-path mismatch parameter.
 27. The IQ mismatchcompensation method of claim 26, wherein the transmitter IQ mismatchparameter is a phase mismatch between an I-path and a Q-path of thetransmitter module; determining the phase mismatch by a difference ofthe I-path mismatch parameter and the Q-path mismatch parameter; andreducing the effects of the IQ mismatch of the transmitter path in thetransmitter module according to a phase compensation matrix of the phasemismatch: $\begin{bmatrix}1 & {{- \tan}\;\theta} \\{{- \tan}\;\theta} & 1\end{bmatrix}.$
 28. The IQ mismatch compensation method of claim 26,wherein the transmitter signal comprises an in-phase component and aquadrature component; setting the in-phase component of the transmittersignal to a first non-zero signal and the quadrature component of thetransmitter signal to the zero signal to generate the firstdown-converted RF signal; determining the I-path mismatch parameteraccording to the first down-converted RF signal and the in-phasecomponent of the transmitter signal; setting the in-phase component ofthe transmitter signal to the zero signal and the quadrature componentof the transmitter signal to the second non-zero signal to generate thesecond down-converted RF signal; determining the Q-path mismatchparameter according to the second down-converted RF signal and thequadrature component of the transmitter signal; and determining thetransmitter IQ mismatch parameter according to the I-path mismatchparameter and the Q-path mismatch parameter.
 29. The IQ mismatchcompensation method of claim 28, wherein the transmitter IQ mismatchparameter is a gain mismatch between an I-path and a Q-path of thetransmitter module; determining the gain mismatch G by a gain equation:$G = {\frac{\left( {1 + ɛ_{I}} \right)}{\left( {1 + ɛ_{Q}} \right)} = {\frac{\sqrt{\left( {r_{I\_ IPATH}^{2} + r_{Q\_ IPATH}^{2}} \right)}}{\left( {r_{I\_ QPATH}^{2} + r_{Q\_ QPATH}^{2}} \right)} \cdot \frac{Q^{\prime}}{I^{\prime}}}}$where: (1+ε_(I)) is the I-path mismatch parameter; (1+ε_(Q)) is theQ-path mismatch parameter; r_(I) _(—) _(IPATH) ² and r_(Q) _(—) _(IPATH)² are the in-phase and quadrature component of the down-converted RFsignal respectively when the in-phase component of the transmittersignal is the first non-zero signal I′ and the quadrature component ofthe transmitter signal is a zero signal; r_(I) _(—) _(IPATH) ² and r_(Q)_(—) _(IPATH) ² are the in-phase and quadrature component of thedown-converted RF signal respectively when the in-phase component of thetransmitter signal is a zero signal and the quadrature component of thetransmitter signal is the second non-zero signal Q′; and I′ is a firstnon-zero in-phase component of the transmitter signal, and Q′ is thesecond non-zero quadrature component of the transmitter signal; and thetransmitter module comprises a transmitter baseband module, coupled tothe loop-back module, reducing the effects of the IQ mismatch of thetransmitter path in the transmitter module according to a gaincompensation matrix of the transmitter IQ mismatch parameter:$\begin{bmatrix}1 & 0 \\0 & \frac{\left( {1 + ɛ_{I}} \right)}{\left( {1 + ɛ_{Q}} \right)}\end{bmatrix}.$
 30. The IQ mismatch compensation method of claim 28,wherein the first non-zero signal equals the second non-zero signal. 31.The IQ mismatch compensation method of claim 25, wherein the transmittersignal comprises an in-phase component and a quadrature component; theIQ mismatch compensation method further comprises: setting the in-phaseand quadrature components of the transmitter signal to zero signals todetermine a first oscillator phase difference parameter; setting one ofthe in-phase component and the quadrature component of the transmittersignal to a non-zero constant signal and setting the other one of thein-phase component and the quadrature component of the transmittersignal to a zero signal to determine a second oscillator phasedifference parameter; determining an oscillator phase differenceparameter according to a difference of the first and second oscillatorphase difference parameters; and reducing an oscillator phase differencebetween the first and second oscillator signals according to theoscillator phase difference parameter.
 32. The IQ mismatch compensationmethod of claim 31, wherein the step of reducing the oscillator phasedifference is performed prior to the step of reducing the transmitter IQmismatch of the transmitter path.